Acoustic tile



Feb- 2, 1950 M. MAccAFERRn 2,923,372

ACOUSTIC TILE Original FiledApril 22, 1952 4Sheets-Sheet1 ZIE- l- D o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o 'o o o o o o o o Q o o o o o o o @v o o o o o o o o o o o o o o o o o O O O O O O O O O O OO 0 O O o o o o o o o o o o o o o o D o o o o o o o Q/oaoo o o o o o o o o o o o o o o Q o o o o o o o o E200/o o o o o o o o o o o o o o o o o o o o o Q o o o o Q l/o o o o o o Q Q O O O O ATTORNEY! Original Filed April 22. 1952 4 Sheets-Sheet 2 I f m 3^ E5- JD- lo T5- JJ- [.0 1\ E A* 30A ./-36 SO/A-V I 36 BY F/(DLQQQ fm 4 Sheets-Sheet 5 ILE--1.3.

jk-F-JE- ACOUSTIC TILE M. MACCAFERRI I: Ji

- Feb. 2, 1960 Original Filed April 22, 1952 uit ATTORNEYS Feb. 2, 1960 M. MAccAl-ERRI 2,923,372

ACQUSTIC TILE 4 Sheets-Sheet 4 Original Filed April 22. 1952 BY Riki/Puk ATTORNEYS States Patent C) 2,923,3721 n AC GUSTIC 5 MariaMaccaferrhRye, N.Y l

Original application April 22, 1,952,2-Serial No.v 283,707, now-Patent No. 2,755,882,.-dated2-July 24,'11956.YA Di-V vided andgthis applicationlpApriLl4;; 1956 SerialtNo. 576,077

`Theinventionis concerned broadly with'the acoustic treatment of wall structures `andrn'ore specifically' is directed to the tile `forms of acoustic treatmentforlap= plication, to or to form the sound" receiving surfaces for such wall structures; and the vnature and objects ofthe invention will be-readily recognizedand understood 'by those skilled in the arts involved in the light` of the followingfexplanation and detailed description ofthe accompanying drawings illustrating what I at present consider to be the preferred embodiments or structural and `acoustical expressions of the invention'an'd the var ions features thereof, from among other forms,- expres= sions, embodiments, modifications, constructions and combinations of which the invention is capable withinthe broad spirit and scope thereof las. denedby the claims hereto appenddl This application is filed as a divisionof my copending application Serial No. 283,707, now Patent No: 2,755,882, ledlAprilZZ, 1952 for Acoustic Tiles;

The various vtypes and forms ofacoustic'tiles which have been proposed by the art fa'lllgenerally intotwo broadftypes -or classes, namely,` tl1`e`type. in which` the tiles are formed of materials whichareinherentlysound absorptive, and the,.type' in whichthe tilesarelfo'rmed of materials which'tare" inherently non-absorptive. Usuallyrin thepractical applications'of both general types the tiles are formed withopenings or'passages4` therein fonthe passage of sound waves therethroughjtov space at .the ,reary ofthe tile ,in which'thereis usually placed some form ofloose sound absorbing,materiaLeither-in' bulkor in the form of mats or pads;

The numerous disadvantagesofboth the sound ab-l sorptive andthe non-absorptive material tilesare` well known to the art and need not'h'ere be recited ,atV length; However, specific attention is directed to' thefact that with both the sound absorptive'and non-absorptive ma-A terial'tiles it is generally impractical andI unsatisfactory to coat, as by painting, becauseof `thereby closing or partially blocking the openings or apertures throughthe tile, so that, itgis not practical to color the exposed surlfaces of the tiles and the decorativeharmonizing lof these acousticaltiles and`hencethe' Wide. application and use-thereof, is limited. Ther cleaning of the exposed surfacesof the tiles is dificult,\whether or not coated, because of the' apertures and the passage of moisture and foreign matter therethrough with' resulting undesirable collections at the rearv of the tile on and in thesound absorbing materialpositioned back of these tiles. Cleaning difficulties are aggravated with the sound absorptive material tiles because of the inherently porous, absorptive characteristicsof such materials; As the non-absorptive material tiles are generally formed of metal or such like hard surfaced, dense material,'it becomes essential to color the exposed surfaces as by painting, and even .if the coating is so applied as to minimize blocking o fcthe tile Yapertures such coating mustberefinished or redone after va certain period: offtime' with the-tiles installed.'A

One'ofithegeneral objectsfof my'invention is to overcome Athe 'colorlimitations of and gth'e necessity for coat# ing or otherwise nishing and treating the various acoustic tiles'of the-art beforelorafter installation, by providing acoustic tiles of materials which-may have any desired permanent color or-colorlvariations and which'lprovide finished surfaces requiringlno treatment' of any character before or after installation, with thefaces or exposed surfacesof 1theI tiles capable# ofreadycl`eaning by 'mere dry wiping or dusting of thef exposed surfacesthereof.

In =carrying out-'the abovegeneraly object, I havev provided acoustic tiles of the dense, hard surfaced-class formed of materials havingjno inherent sound absorbing characteristics; and ak furtherimportant object isV to so design and construct'such aftile asto cause the tileto itself function to damploutf and dissipate a substantial percentage of the `sound energy or waves striking against the exposed surface thereof 'by damping out the striking sound waves.

Another objectis toprovide anacoustic tile having vibratory` damping tubes projected'from the inner side of the tile withv sound receiving passages through the tubesopening through `the-Konter, sound wave receiving surface of the tiledbody;

I have discovered that certain thermoplastic synthetic resinsg such as-a'fpolystyrene'- have when molded the requisite structural andivib'ratoryorl resonance response characteristics from which to efficiently 'form' an acoustic tile having the foregoing;featuresirrl construction and functioning; anda further object-'is' to` provide a design and construction' for such fa' thermoplastic acoustic tile which 'y will' permit of the' tiles-being eiciently manufactured'on a quantity production' basis with" standard types of molding equipment ati'relatively low production costs per'tile.v i

A further object is to provide a thermoplastic material acoustic tilewhichlcanuberreadily` andicheaply installed in attachedpositio'non aWalllor-otherstructure without theV use of special Vtoolsor equipment by unskilled-installers, and with a `minimum ofitileL surface marring and *ofitile' breakage.'v

Another object is to provide a modified form of'the thermoplastic .acoustic .tilehaving the-sound 'wave damping andw'energy dissipating:features'rreferred to herein-i above, which will be particularly eflcient-for those types of installations in which the tiles are to bezpositioned and securedv by manually'pressing vthefftiles Yinto an unset mastic coatingapplied to the structure to1be acoustically treated with the tiles;`

A further 'object` is tto f providewa construction Y of such a-mastic installableVV tile infwhich-members are provided projected rearwardly from fthetfrearnside, of? the tile with the -rear ends of such members formedt into cups for engagementin the unsetmastic ontol'which the tileis With the ,foregoingl and various otherObjectS, features and results in View whichwill beareadily; apparent from the following description.andrexplanatiorn my. invention consists in certain novelfeatures in designconstruction,-, materials and forms and in combination of elements, all as will be. more fully' andpartic'ularly referred to and described hereinafter;

Referring to' the accompanying drawings in which' similar reference characters refer to corresponding parts and elements throughout the several figures thereof.

Fig. 1 is a view in plan of the front or face side of an acoustic tile of my invention -of a form thereof vhaving the multiplicity ofsound wave damping tubes projecting from the rear side thereof.

Fig. 2 is a view in edge elevation of an acoustic tile of Fig. 1 in installed position. f Fig. 3 is a view in plan of the rear side of the tile of Fig. 1 showing the multiplicity of damping tubes thereon.

Fig. 4 is a fragmentary view in transverse section taken as on the line 44 of Fig. 1.

Fig. 5 is a transverse sectional view taken as on the line 5-5 of Fig. 3.

Fig. 6 is an enlarged fragmentary view in longitudinal section through one of the integraldamping tubes and the example tile is formed with a continuous, narrow,

'shallow depth integral flange therearound which is comprised of an outwardly and rearwardly inclined wall or panel along each side of the tile and which terminates along its rear edge in a wall disposed normal to the plane of the front Isurface of thebody of the tile, such rear wall of the flange having j a straight, planar outer surface also normal to the plane of thetile vbody front surface or face.v The inclined panel and inner or rear wall thereof along each side of the' tile body are integrally joined at their opposite ends with the ends of the inclined panels and rear edge walls of the adjacent sides of the tile to form in eiect the four corners of the tile the base construction thereof which joins the tube with the tile in the form of tile of Fig. l.

Fig. 7 is a view in longitudinal section through a modiied form of the recess formed in the rear side of the tile body around'the base of a damping tube.

Fi 8 is a View in lon itudinal section throu h an- '5 g g g has plan dimensions of lll/2 x lll/z and a resulting other modified construction in which the recess around the base of a damping tube is eliminated.

Figs. 9, 10 and 1l are sectional views of further modiiied forms of the damping tubes shownV in Figs. 6, 7y and 8, respectively.

Figs. l2, 13 and 14 are sectional views of still further modifications of the damping tubes shown in Figs. 6, 7 and 8, respectively.

Figs. 15, 16 and 17 are sectional views of modifications of the damping tubes in which each tube has the rear end thereof closed by an end closing wall.

Fig. 18 is a sectional view through a form of the closed end damping tube of Fig. 17 having a cup at the inner, closed end of the tube.

Fig. 19 is a sectional view through a modified form of the cup tube of Fig. I8.

Fig. 20 is a view in plan of the face side of a modilied form of tile in which the damping tubes at the rear side of the tile in the form of Fig. l have been eliminated with the tile having a multiplicity of sound wave receiving openings therethrough, a portion only of the tile being shown. Fig. 21 is a view in transverse section through the portion of the modified tile of Fig. 20, taken as on the line 21-21 of Fig. 20.

I have selected examples of tiles of my invention in which the tile is square in plan and has maximum outside dimensions of l2" by 12", that is to say, each tile of the selected examples presents approximately one (l) square foot of wall covering when in installed position. A tile of this approximate size is generally consideredby the art as a tile adapted primarily for ceiling installation but it is to be understood that with the plastic tile of my present invention due to the design and construction thereof and to the visual appearance of the tile when in installed position, these so-called larger area or ceiling tiles may be as readily eifectively used, if desired, for installation for the acoustic treatment of side walls. Hence, there is no intention by the disclosed examples of larger area tile to in any way limit the intended use thereof, or the use for which such tile are or may be found to be adapted. v

All of the tiles of the examples have the common characterisic of having been injection molded into the form of a thin, flat sheet or plate of a thermoplastic material forming the body of the tile and having a thickness within the range of the order of .05" to .10", that is to say, approximately lo to 1,50". In the particular examples of polystyrene tiles hereof, the bodies of both the preferred and the modified forms of tile have ak maximum'thickness of-approximately .06 ".v Each of unit. In the tile embodiments hereof the inclined panels and inner or rear edge walls making up the continuous flange of the tile are of uniform thickness throughout that is the same as the maximum thickness of the tile body, namely, .06. The outer side, planar surface `of the inner'edge wall of the flange along each outer side of the tile body is located in a plane spaced a distance of l/zf from the inner, forward edge of an inclined wall along which such wall joins the front side or face of the tile body. Hence, the square face of the tile body area of 132.25 square inches. However, the, variou`s features of the invention are not limited or restricted to any particular size of tile or surface area of the face Y thereof, but may be embodied in larger, sheet-like sizes,

. thin, sheet-like plate 10 having a maximum thickness of approximately 0.06", and providing the flat, planar front surface or face 11, and the flat rear surface 12. The tile body hasl the continuous integral flange therearound comprised by the outwardly' and rearwardly inclined panel or wall 14 and rear edge wall 15 thereof along each of the four side edges of the body 110. The rear Wall 15 of each panel14 is formed'with a straight planar rear edge surface 15a which is adapted to forman elongated seat to abut and seat against the surface of a wall W or other structure as schematically indicated in Fig. 2 of the drawings. The inclined panel 14 and rear' edge Wall 15 along each side of body 10 are integrally joined at their opposite ends with the ends of the panels along' adjacent sides to thereby form the beveled corners 14a of the tile unit. Thus, the rear edge walls 15 of the tile flange together form a hollow-square seating base for locating and positioning the tile in installed position on a structure to be acoustically treated. In the example tile, the rear edge surfaces 15a of the tile flange lie in a plane spaced approximately 1A from the plane of the front surface or face 11 of the body of the tile, so` that with the tile in installed position on a wall, the tile body is spaced outwardly from the surface of the wall a distance to provide a space S which is enclosed within the tile ange between thetile body and the wall (see Fig. 4). Thus, the flange is narrow or of shallow depth rearwardly relative to the plane dimensions of the exam-A ple tile. The outer side of each rear edge wall 15 of the continuous flange of the tile, is formed to provide a precisely planar surface 15b normal to the front surface or face 11 of the tile, for accurate abutment against the corresponding surface 15b of an adjacent tile in an installation of tile, so that a clean, visually satisfactory joint between adjacent tile may be had with the joint so formed in effect providing a seal against the passage of foreign material therebetween. The tile unit comprised of the body 10 and the continuous integral flange 14-15 therearound is formed of an injection molded polystyrene in the example hereof, and, due to the physical and structural characteristicsof injection `molded polystyrene, the tile may be com mercially produced with dimensional stability and dimenf and coincident with the center of an aperture aaa-sa sional-precision. It is' iherefo'repessible withstwhthjerrne plastic' to produce a tile of the form illustrated, with sharm-clear cut edges along und between the ange walls 14""a'nd the front surface or face 11 of the tile andl between such walls 14 and the rear edge forming walls 15 of the tiange,'with the inclined walls'14 being precisely planar and giving a clean, beveled appearance tothe tile. And d ue to the characteristics of the material, the precision of theplanar surfaces 15a and 15b may be attained by the injection molding of the tile, without requiring any machining, grinding, polishing or other finishing operations on the tile after the molding thereof'.

'*The tile body 10 of the form of the tile of Figs. 1 throughv, is formed' with a multiplicity of circular apertures, openings or holes 2t) distributed over the entire arrealof the platelike body of the tile and opening through the front, exposed4 surface of face 11; thereof. The area of thefront surface or face 11, in this example, s 132.25 square inches, andi have formed each circular aperture 20 of a diameter of 5/32" at the surface 11, and provided a total of 289 of such apertures'of that particular diameter. These 289 apertures are arranged and located over the area of surface 11 of tile body 10, in seventeen parallel rows spaced equal distances apart across the surface 1'1 with each row being comprised of seventeen (17) apertures spaced equidistant apart along the row formed thereby. Hence, there results a pattern l of apertures through the surface 11 in an equal distribution over the area thereof, which is comprised of seventeen (17) rows 4of seventeen (17) apertures each across the tile parallel with opposite edges thereof in one direction, and seventeen (17) rows of seventeen (17) apertures each across the tile in a direction perpendicular tothe first mentioned rows. By thus arrangingand distributing the aperture 2G, each aperture of the 289 apertures lis located with its center spaced 11/16" from the center of the apertures of the pattern next adjacent thereto inseither'direction aiong either row in which an aperture is located. In the example pattern arrangement the outermost row of apertures 20 along and parallel with each'straight side edge leb of the tile surface 11, has the apertures located with their centers spaced a distance of 1/4 from'such adjacent edge 14b.

.With'the tile thus apertured and comprised of the thin, plate-like body tiiand the flange 14`-15, formed of an injection molded thermoplastic, .suchV as a polystyrene, Ij have'provid'ed' as an important feature of my invention, both acoustically and structurally, a multiplicity of vibratory, sounddamping tubes 30 integralv with thev tile body`10 and projecting rearwardly from the rear side 12 thereof at each location of an aperture 2t) through the body. Referring to Figs. 5 and 6 inparticular, each damping tube is formed of a'wall 31 of cylindrical cross section and of a thicknessless than the thickness of the tile body 10, say of an approximate order of 0.03. Each thin-walled dampingV tube'30 is molded asanintegral part of-the plate-like body 1t), and is disposed in position projected rearwardly from the rear wall 12of the body with-its axis normal to the plane of the body face 12 20 through the`body. Each tube provides a bore or cylindrical passages 32 therethrough having the same diameter as the diameter of an aperture 20, namely 5/32" in this instance, Sio/that the aperture 20 at which a tube is located provides the sound wave inlet opening through the body 10 from they front exposedrface 11 thereof vinto the body l'from the'front exposed face 11 thereof'into the passage 32 of the tube. l The length of each tube4 30 is lessthan the dis.- tance"betweentheouter surfaceorv face 11' of the tile body 10 and thepplane' passing throughwthe rear, seating edges `15'a`of the tile'flange 14515, that is to say, less than theidistance"` between bodyl and the front surface of a wall W' (see'Fig. 4) witbthe tile in installed position on thewall'. Thus, the'tubes'30gare free at their inner efds with a'l'tile installedona wall as a componentof vibratory damping tubes 30 is open to provide theV sound wave dischargeoutlet or openingv 32' from the tube. I n this preferred form of tube, the passage 32 therethrough is of constant diameter and theV end discharge opening has the same'vdiameter as the passage and as thevr inlet aperture 20 in the tube body 10. y n

As'a further feature of the preferred form of damping tube, and as a factor contributing to the vibratory response of the tube to sound waves entering into and passing through the passage 32V of the tube, I have provided a construction at the base of each tube where the tube integrally joins with the body 10, by which the tube base is of' reduced thickness relative to the thickness of the body 10. I have in the preferred expression of such a reduced depth for the base of a tube 30, referring now to the enlarged detail View of Fig. 6 in connection withFig. 4, provided -an annular recess 33 in the rear side 12 of the tile body 1 0 around each damping tube 30, with each recessbeing tapered or inclined radially outwardly from and around the'inner or base end of the tube to the rear surface 12 of body 10. A recess 33 thus has its greatest depth at and around the outer surface of the thin wall 31 at the inner end of the tube at the line of integral joindure of the inner end of the tube with body 10. By this construction the thickness of body 10 is reduced around the aperture 20 which forms the inlet end of the tube to provide a reduced thickness mounting base 34 which integrally joins the tube with the tile body, as will be clear by reference to Fig. 6. The forward wall 33d of the recess 33 may be flat to form a radially outwardly and rearwardly sloping planar surface, or may be formed concave or even convex while retaining the essential function of reducing the thickness of the body around and immediately adjacent the inner end of a tube 30 and the aperture 20 thereof, to provide a base portion 34 having a more sensitive vibratory response.

With the tile unit of this vibratory tube form secured in mounted position installed onand over a wall surface such as the surface W as indicated in Fig. 4 of the draw-- ings, the tile is positioned by the flange rear edge surfaces'.

15a seated against the wall surface with lthe multiplicity of tubes 30 projecting rearwardly from the rear side 12 of the tile body 19, into the space enclosed with-in the tiles. As the tubes 30 have a length less than the depth, of the space S, the rear ends of the tubes are positioned spaced from and out of contact with the wall W, and are thus free to vibrate without interference with or con-- straint by either the tile or the wall structure. The polystyrene thermoplastic of which the tile is preferably formed, has when injection molded the characteristics ofl density and of surface hardness, and may be consider-edi non-absorptive of sound waves striking against the hat'd front surface or exposed face 11 of the body 10 of the tile. However, with the great multiplicity of aperturesy 20 evenly distributed in a relatively closely spaced rela-4 tionship over the entire area of face 11, a substantial percentage of the sound waves striking against surface 11. will enter into and be absorbed by these apertures, so: that the striking waves will be effectively broken up asf well as absorbed in the apertures with a resulting initial. sound wave deadening effect. The effectiveness of the tile acoustically is substantially increased by the entry of the percentage of waves into the apertures 20 and the passagey thereof through the tubes 30 and discharge from :the inner endsl of the tubes into the space S at the rear of the tile. Passage' of sound waves into and through tubes 30 induces or sets up vibration of the tubes, so` that'the sound energy is substantially expended and dissipated in effecting such vibration of tubes. In this manner a suflicient proportion or percentage of sound waves striking the tile body will be dissipated and de-y stroyed to effect a substantial sound absorption with a. minimum of reflected or induced waves being thrown b'ckor projected from the tile body 10, notwithstanding form of the body 10. Any sound waves which are not effectively damped out and expended in effecting vibrations of the tubes 30, or any of them, will be discharged from the free inner ends of the tubes into the space S at v the rear side of the tile and there dissipated and absorbed within such space.

In order to buttress the acoustic tile of the form of the preferred example, and to provide additional, rigid seats against which the tile may be rmly attached in installed position, I have provided a plurality of integral, cylindrical bosses 40 located at strategic positions on and projecting rearwardly from the rear side 12 of the tile body 10. Referring to Fig. in particular, each of these bosses has a at, Vplanar seating surface 41 across the rear side or end thereof which lies in the plane passing through the continuous seating edge 15a provided by the rear edge of the tile ange 11i-15. In the arrangement of this example such bosses 40 are distributed and located as follows: `One at each corner of the rear side 12 of the tile body; one midway along each edge of the tile body; one -at the center of the rear side of the body; and one at the center of each quarter section of the tile rear surface. Thus, with the relatively largearea of the very Y thin tile body 1t), when ithe tile is attached in installed position on a wall, the rear ends 41 of the bosses 40 are engaged against the surface of the wall and support the tile body 1t) against bending or exing inwardly toward the Wall to thereby maintain the front side or face 11 of the tile body as a substantially true, flat, planar surface.

`Obviouslyany other suitable or desired arrangement of locations may be utilized for the bosses 4G, and any number thereof may be used, as my invention is in no sense limited to the number or arrangement of the bosses provided on the example tile.

As the tile of the example form of Figs. l through 6, is of the type to be secured in installed position on a wall by mechanical fastening means, such as nails, I have devised a design and location of the bosses 4t) by which they provide the members -for nailing attachment to a wall or other structure and by which they utilize apertures 20 of the tile body for receiving the nails to be driven therethrough. For example, each boss is of tubular form and is formed on the rear side 12 of the tile in position with the bore 42 of the boss axially alined with an aperture 20 which aperture thus provides the front, nail receiving opening of the boss. The rear end of each nail receiving boss 40 is formed with the end wall 43 which provides across its outer side the seating surface 41, as referred to hereinabove. This rear end wall 43 is formed with an axial bore or opening 44 therethrough in Iaxial alignment with the bore 42 and the aperture 20 through the face of the tile body, with the opening 44 having a diameter less than the diameter of bore 42. There is thus formed an annular seat 44a around the opening 44 within the boss 4i? against which the head of a nail is driven and seated. In this manner a countersunk nailing opening through the tile body and each integral boss 40, is provided as clearly shown in Fig. 5 in particular, so that, the tilemay be nailed into attached,rinstalled position by driving the nails through the boss bores 42 and rear nail openings 44 into tile securing position with the nail heads engaged against the seats 44a in position countersunk within the bosses.

With the preferred form ofthe tile of Figs. 1 through 6,

having the plan dimensions and the thickness for the tileV body as heretofore stated, the ratio of the aggregate area of all of .the 289` apertures 20 each having a diameter of g, to the total surface area of 132.25 square inches of the tile face 11, is considered to be effective in sound absorption or deadening. However, this ratio may be varied not only in the size tile of the example, but in tiles of different face areas, although it is considered that which a recess 33 of greater area and flatter slope to the wall formed thereby is provided. By the construction of Fig. 7, a reduced thickness base 34 is formed for a tube 30 than the base 34, to form in effect a relatively thin base disc for and with which a tube is integrally joined.

And while constructions of the base of the vibratory tube as shown in Figs. 6 and 7, offer certain advantages in vibration sensitivity and response for a tube, a construction such as shown in Fig. 8 may be employed with effective results with a tile of the form of Fig. 1. With the construction of Fig. 8, the recesses, such as 33 or 33 at the rear side 12 of the tile body 10 are eliminated, andv substantially the full thickness of the tile body is maintained to and integrally joins with a tube 30. Such construction makes for a stiffer and more rigid tube base but still retains the free end, vibration responsive, thinwalled tube for effective sound wave'damping.

In Figs. 9, 10 and V1l, I have shown a variation of the damping tube wall construction for tubes having the types of bases of Figs. 6, 7 and 8, respectively. In the illustrated variation the damping tube 30A has in each instance a wall of slightly greater thickness than the very thin wall 31 of a tube 30, with the bore through the tube being of constant diameter but with the outer surface y36 of the tube wall being progressively tapered inwardlyfrom the base to the rear, free end of the tube. There is'# thus provided a damping 'tube having a wall thickness which progressively decreases from base to the rear, free end thereof.

A further variation of the damping tube is disclosed in Figs. 12, 13 and 14, by a tube 30B having a thin wall 37 of approximately the thickness of the wall 31 of a tube 30, but with the wall 37 of uniform thickness throughout its length and being progressivelyy tapering from the base to the rear, free end of the tube. Such form of tube provides the bore therethrough as being of progressively decreasing diameter from the base to the free rear end of the tube. The tube 30B is shown in Figs. 12, 13 and 14 as having bases of the types shown for the tube 30 in Figs. 6, 7 and 8, respectively.

If desired or found expedient the damping tubes of any of the forms and constructions may be provided with the rear free endsrthereof closed by an end wall formed integral with the tube side wall. As an example I have illustrated such a closed end tube 30C in Figs. 15, 16 and 17 as applied to the tube of the form shown in Figs. 9, 10 and 11. A tube of the form of tube 30C has a at end wall 38 molded integrally with the tube to extend completely across and close to the rear end of the tube. The tubes 30C of Figs. 15, 16 and 17 are shown integrally joined with the tile body 10, by bases of the types shown in Figs. 6, 7 and 8, respectively. While the closing of the rear free ends of the damping tubes may decrease theacoustic efliciency thereof and of a tile on which used, yet the closed chambers thereby formed having the sound inlet apertures 20 through the face of the tile body will have a substantial sound wave absorbing effect, particularly with a distribution of such tubes with the sound absorbing chambers therewithin, in great multiplicity over the face of the tile body in an arrangement such as shown in Figs. 1 and 3 of the drawings.

A thermoplastic (tile of my invention in accordance with a modified form thereof illustrated in Figs. 20 and 21, may eliminate the damping tubes of the forms.A of Figs. 1 through 6 and the several disclosed variations thereof, and provide the tile body 10'- as solely a thin into the space at the rear of the tile.

. 9 plate having only the mountingand nailingl bosses 4Q provided in any' desired arrangement on the rear side thereof'. -In Fig. 20, a quarter section of the., front side of such a tile isshown havingk a number anddistribution of apertures 20 therethrough similar to that provided for the preferred form of tile of Fig. 1. The rear side 12' of the tile body 10 is. formed' with au annular rearwardly and outwardly tapered' recess 33u therein surrounding andconcentric with each aperture 20. Each recess 33a extends into the body 10 of the tile toits face aperture 20" with the latter forming the smaller. diameter sound wave inlet opening of a rearwardly tapering passage havingl its large diameter discharge opening through the rear surface 12 of the tile body.

This modified formk of tile of Figs. 20 and 21, will without the damping tubes of the preferred form, give an effective performance acoustically for certain characters -and conditions ofl installation. Due to the distribution and number of the apertures 20', which apertures may be taken to each be of the diameter f an aperture 20 of the preferred form, -a substantial and effective percentage of the sound waves striking the face of the tile body 10 will enter and will enter and pass through the apertures 20 and the rearwardly tapering` passages provided by the annular recesses 33a, Such sound waves will thus be dissipated and absorbed.

The modified form of tile of Figs. 20 and 21, lends itself to the mounting of sound absorbingmaterial in the spaceat the rear of the tile, where in any installation it may be found desirable to do so.

Instead of providing the recesses 33a as of aprogressive taper to the frontsurfacer o rjface 11 to form and define each aperture' 20 by a short, thin circular edge, as in the example illustrated, the aperture may be formed of greater depth by a constant diameter passage which joins and opens into the recess atan intermediate location within the tile body.

The preferredform ofthe tile of Fig. 1 and the moditiedform of Fig. 20, are both shown as being of the nailV attachment type, but bya further feature of'my invention 1I have provided a form of the tile having the multiplicity of sound wave receiving tubes so designed as to render the tile capable of efficient installation by means of a mastic and without the necessity of mechanical fastening means.

In order to increase the holding effect of the closed end tubes when engaged in the still unset mastic, I have devised a form and construction by which a cup is provided at the rear closed end of the tube. Referring to Figs. 18 and 19, I mold the tile with the closed end tubes 50 thereof provided with a rearwardly extended fiange or skirt 53 therearound in continuation of the tube Wall. Thus, flange S3 provides at the rear end of the tube a cup 54 which is closed at its inner or bottom side by wall 52 and at its outer side by iiange 53, with its rear side open. In one form of such tube and cup `as exemplified by Fig. 18, I may make the overall length of the tube 50 and the flange 53 such that the rear edge o-f the flange lies in the plane of the rear edges 15a of the tile flange.

In another form of such tube and cup as shown in Fig. 19, I form the flange 55 as of greater length than the ange 53 of Fig. 18, and then bend or form the flange to are or extend radially outwardly from and around the tube to thereby provide a key or anchor for engagement in the mastic. With the form of Fig. 19, the cup 54 will function primarily to hold the tile in position while the mastic is setting. After the mastic is set the key or anchor ange 55 then firmly and rigidly holds the tile in installed position. I may curl or press the fiange 55 into final form by molding it straight as indicated in Fig. 19, and then pressing or forcing the flange against a hot plate to soften the thermoplastic andcause the ange to be pressed outwardly'into. its radially flared, anchor forming shape,

My invention contemplates and includes tiles which are'provided with the majority of the damping tubesjhaving open, sound wave discharging rear ends, such as the tube forms of Figs. 6 through 14, together with. a sufficient number of closed end tubes, with o r withoutv end cups, such as shown in Figs. 18 or 1.9, for anchoring or keying in a mastic to permit of the mastic installationl of the tile.

The invention provides as a new article of manufacture an acoustic tile in several forms and types, injection molded of a thermoplastic material, such for example as a polystyrene and the designs and constructions of such tile as to certain of the essential features thereof utilize certain of the physical characteristics of an injection molded thermoplastic material to attain increased acoustical and structural efficiency, and to make it possible to produce a complete tile structurally and in finished form by a single injection molding cycle with standard injection molding equipment. However, the invention is capable ofy expression in othery thermoplastic materials than a polystyrene, and as to certain features thereofv in other materials than thermoplastics. Hence, it is notintended to restrict the invention and` the several features thereof to use only in a polystyrene. tile. Similarly while the thermoplastic material `tile may be preferably formed by injection molding, it is not intended to so restrict the invention as it includes the formation of the tile by other moldingy methods.

It will also be evident that various other modifications, embodiments, combinations, substitutions, eliminations', as well as various composite arrangements ofthe several forms and variations shown, might beA resorted to without departing from the broad spirit and scope of my invention, and hence I do not desire to limit the invention in all respects to the exact and specific disclosures of the several examples hereof, intended specific limitation thereto appearing in any of'the claims hereto appended.

What I claim is:

1. As a new article of manufacture, an al1-plastic acoustic tile formed of plastic material comprising, in combination, a thin plastic material body of plate form; a rearwardly extending edge ange of plastic material around said body integral therewith; said edge fiange having a narrow, shallow depth relative to the plan dimensions of said body; said thin body having a front side providing a face surface thereover and an opposite rear side providing a rear surface thereover surrounded by said shallow depth edge flange; said body having a multiplicity of small diameter apertures closely spaced over the area of said face surface extending through said body from and opening through said face surface to and opening through said rear surface of said body over the entire area of said rear surface; a multiplicity of vibratory sound wave damping tubes of plastic material integral with said body projecting rearwardly from the rear side thereof; each of said plastic material damping tubes having a passage axially therethrough and being located on the rear side of said body in positions with said axial passages aligned with and opening into said body apertures, respectively, with the latter forming the inlets to said tube passages through said tile body; each of said plastic material sound wave damping tubes being relatively thin walled with the thickness of the wall thereof being less than the thickness of said thin plastic material body for vibration response by said damping tubes to sound waves to which subjected; said multiplicity of thin walled, vibratory plastic material damping tubes extending in uniformly closely spaced relation rearwardly from and over the entire area of said rear surface of said tile body; and said vibratory plastic material damping tubes extending rearwardly throughout substantially the full depth of said narrow, shallow depth edge flange 11 with the rear ends thereof located at the rear edgey of said edge ange in a plane in immediate proximity to the plane in which -the rear edge of saidedge flange is located for free Vvibration of said plastic materialdamping tubes.

2. As a new article of manufacture, an `all-plastic acoustic tile formed of a molded plastic material, comprising, a plate-like body having a rearwardly extended edge flange therearound integral therewith; said body being formed to provide the front side thereof as a at, planar face and having a multiplicity of apertures therethrough from said front face to and opening through the rear side of the body; sound wave damping tubes molded integrally with said body projecting rearwardly from the rear side thereof; each of said damping tubes having a passage therethrough open at the rear end thereof; each of said damping tubes being located on the rear side of said body in position with a body aperture opening into-and forming the inlet to said passage of said damping tube; and said body having the rear side thereof formed with an annular recess therein around each of said damping tubes providing a reduced Ithickness base portion of the body with which the tube is integrally joined.

3. As a new article of manufacture, an all-plastic acoustic tile `formed of a molded plastic material, said acoustic tile comprising, a plate-like body having a rearwardly extending edge ange therearound integral ytherewith; said body having a front face side and a rear side surrounded by said edge flange; said body being provided with a multiplicity of apertures therethrough from said front face side to and opening through said rear side thereof; sound wave damping tubes integral with said body projecting rearwardly from the rear side of said body; each of said damping tubes having a passage therethrough open at the rear end of the damping tube; each of said damping tubes being located on therear side of said body Yin position with a body aperture opening into and forming the inlet to said passage in the damping tube; said body having the rear side thereof formed with an annular recess therein around each tube and through which each tube extends; and said recesses havingtheir greatest depth at their respective tubes and progressively decreasing in depth radially outwardly from the tubes along the rear surface of said tile body.

K4J As a new article of manufacture, an acoustictile formedV entirely of plastic material, comprising, in cornbination, a thin body of plate'form having a narrow, shallow depth, rearwardly extending edge ange therearound integral therewith; said body having a front face side and an opposite rear side surrounded by said edge flange; said body having a multiplicity of apertures therethrough spaced apart over substantially the entire area of said front face side; said apertures opening through said front face side and extending through saidbody to and opening through said rear side thereof; sound wave damping tubes integral with said body projecting rearwardly from said rear side thereof throughoutsubstantially the depth of said shallow depth edge flange; each of said damping tubes being located in position on the rear side of said body with one of said apertures opening into and forming the inlet into the forward end of each such damping tube; and the portion of said body of said tile around and adjoining each of said damping tubes being of reduced thickness relative to the thickness of said body in the remaining areas thereof between said damping tubes and said portions of said 'body of reduced thickness.

`5. An acoustic tile in accordance with claim 4, inV

which each of said sound wave damping tubes has the rrear end thereof closed by an end wall.

. References Cited in the le of this patent UNITED STATES PATENTS 

